The Shapechanger Scenario

When humans arrived at Draconis 9, the only life on the planet was docile race of mammals. Humans do what they always do when they arrive on a new planet; they begin to kill things. It turns out the mammals were tasty. Little did the colonists know the animals were actually a race of telepathic shapechangers. Faced with being hunted for food, the shapechangers took the form of humans and began to learn how to face their new predator. The race was docile no longer.